This topic develops a formal description of magnetic fields and moves on to electromagnetic forces and induction.

The scheme described follows a fairly standard approach that is similar to the order in which the topics appear in most exam specifications. The three main electrical machines, motor, generator and transformer, are covered at the end so that all the relevant physics will have been covered before they are discussed. It would be possible to introduce motors after Episode 412 but there would be problems in discussing back emf and eddy currents at this stage. Transformers can be used as a way of introducing the ideas of episode 415.

An alternative approach might be to introduce the idea of flux via the transformer and generator, offering a different way of thinking.